1,720,956 research outputs found
장주기 운전을 고려한 가압경수로 방사화 부식생성물 평가 연구
No full text학위논문(석사) - 한국과학기술원 : 원자력공학과, 1999.2, [ viii, 52 p. ]Nowadays nuclear power plant operation practice shifts to extended fuel cycle such as from 12 month operating cycle to 18~24 month operating one. It is important to emphasize that the current trend to longer fuel cycles has complicated the dilemma of finding optimum pH range for the primary coolant chemistry. Typically, current 12-month fuel cycles start with no more than 1200ppm boron concentration at the start of a cycle, so a maximum value of 2.2ppm lithium is supplied to satisfy the pH6.9 requirement. The occupational radiation exposure (ORE) increases due to radioactive corrosion products. The recent ICRP recommendation (ICRP publication No. 60) for the radiological protection requires more strict reduction of ORE in the nuclear power plant. The major sources of the radiation are generated by the neutron activation of the non-radioactive corrosion products, that is called CRUD(Chalk River Unidentified Deposit).
To optimize the chemical conditions at the extended fuel cycle, COTRAN code which was developed to simulate the behavior of the radioactive corrosion product(CRUD) was used. COTRAN code was developed to estimate CRUD during only one cycle. This study, however, is to predict corrosion product not for one cycle, but for multi-cycle. In order to predict corrosion products for multi-cycle, COTRAN code is modified for considering decontamination, refueling and applied to KNGR.
The results show that not only selecting the optimum pH but also cycle duration are important parameters reducing the generation of CRUD. It turned out that the activities of CRUD decreases as pH of the coolant increases, and for the same period of different fuel cycle, as the fuel cycle duration increased, the generation of the CRUD increases. As operation cycle duration is increased, the ratio of becomes small. Activities of and shows similar trend to measured activities of those at steam generator tube surface of Millstone Point 3 PWR.
It is...한국과학기술원 : 원자력공학과
원자력발전소에서 발생되는 방사성부식생성물의 자기적 성질을 이용한 제거방법에 관한 연구
No full text학위논문(박사) - 한국과학기술원 : 원자력및양자공학과, 2004.2, [ x, 130 p. ]It is important to emphasize that the current trend to longer fuel cycle (1824 month) has complicated the dilemma of finding optimum chemical condition for the primary coolant because of some problems such as increase of radioactive corrosion product, possibility of axial offset anomaly and so on. Radioactive corrosion products which are generated by the neutron activation of general corrosion products at a nuclear power plant are the major source of occupational radiation exposure.
There are several ways to reduce the radiation levels around the primary water system. For example, improving the coolant purification system, operating at high pH, the adopting materials with low levels of cobalt in the primary coolant system and decontaminating the primary system more frequently. The representative method for CRUD reduction is the high pH operation that controls the deposition of general corrosion products using solubility difference in the primary coolant system. The pH value of 7.4 has been suggested as suitable pH value in many experiments and researches. However, it is difficult to operate on the high pH chemistry at the long term fuel cycle (1824 month cycle) due to high boron concentration. The concentration of lithium that works as chemical agent with boron in order to control pH of the primary coolant is restricted because of possibility of Li-Zr stress corrosion cracking related to nuclear fuel damage. Therefore, it is important to emphasize that current movement to long term fuel cycle has increased the difficulty of pH optimization. Amounts of CRUD generation at long term fuel cycle expect to increase compared to 12 month fuel cycle owing to difficulty of high pH operation.
Not only passive ways for CRUD reduction but also active methods for CRUD removal are required at a long term fuel cycle. During the power operational period, the crud in the primary coolant is generally removed at the chemical volume control system (CVCS), which controls the concent...한국과학기술원 : 원자력및양자공학과
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
전임자의 비자발적 사임이 새로 임명된 경영자의 이익 조정에 미치는 영향
Full text link학위논문(석사)--서울대학교 대학원 :경영대학 경영학과,2019. 8. 황인이.This study explores whether forced turnovers influence the newly appointed CEOs opportunistic behavior. Prior literature finds that CEOs overstate earnings greater in the early years than later years of tenure. However, this study finds that this earnings overstatement trend is disappeared when predecessor is likely to be forced to leave. In this case, the newly appointed CEOs hesitate to overstate earnings in the early years, and this mitigates the difference in earnings manipulation between two periods.본 연구는 최고 경영자의 비자발적 사임이 이후 임명되는 새 경영자의 이익 조정에 어떠한 영향을 주는지에 대해 다루고 있다. 선행 연구에 따르면 최고 경영자의 재임기간 중 초기 이익 조정이 말기 이익조정보다 크다는 것을 밝혔다. 본 연구는 이러한 경향이 전임자의 자발적 사임과 비자발적 사임에 따라서 달라지는지 분석하였고 그 결과 비자발적 사임의 경우 재임 초기와 말기의 이익 조정 차이가 사라지는 것을 발견하였다. 특히, 비자발적으로 사임된 경영자 이후 새로 임명된 최고 경영자가 재임 초기에 이익 조정을 주저함으로써 초기와 말기의 조정 차이가 줄어드는 것을 발견하였다.1. Introduction 1
2. Hypothesis Development 5
3. Empirical Research Design 10
3.1 Type of CEO turnover 10
3.1. Earnings Management 12
3.2. Estimation Methodology 14
4. Sample and Descriptive Statistics 18
5. Empirical Results 19
5.1. Earnings overstatement analysis based on type of CEOs departure 19
5.2. The difference in Earnings overstatement of newly appointed CEOs 20
6. Limitation and Further Study 22
7. Conclusion 23Maste
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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